XMM-Newton campaign on ultraluminous X-ray source NGC 1313 X-1
By Ciro Pinto,
The Athena X-ray Integral Field Unit (X-IFU) is expected to revolutionise the study of accretion flows in the coming decades. Their narrow spectral features are unique probes of the structure of accretion discs around compact objects such as black holes. To better understand winds in ultraluminous X-ray sources (ULXs) and their super-Eddington accretion mechanism, we have undertaken a major campaign with XMM-Newton to study the ULX NGC 1313 X-1. The campaign showed that the wind varies with the continuum in agreement with the theory, but the current instrumentations do not allow to probe the most crucial variability time scales. Our simulations show that Athena's X-IFU will boost the detectability of the spectral lines imprinted by the outflowing plasma in ULX spectra with exposure times of a few minutes. The novel study of line vs state variability will break the current model degeneracies, shedding new light on the structure of the accretion discs and the overall super-Eddington mechanism.